Stain Remover Containing Fluoropolymer

ABSTRACT

A stain remover which comprises a copolymer made from as essential ingredients (a) a polymerizable monomer having a polyfluoroalkyl group with less than 8 carbon atoms and represented by the general formula H 2 C═CXCOO—Y-Rf and (b) a fluorine-free polymerizable monomer represented by the following general formula: H 2 C═CXCOO—(RO) n —X. The stain remover is effective in minimizing the amount of an organic solvent to be used. It imparts to a substrate the excellent property of removing stains therefrom and a satisfactory texture.

TECHNICAL FIELD

The present invention relates to a soil release agent used for a textile and the like. Particularly, the present invention relates to a soil release agent which comprises a necessary minimum amount of an organic solvent and which has excellent soil releasability and good handling.

BACKGROUND ART

As a soil release agent (also referred to as “SR agent”) which makes easier to remove a soil adhered to an treated article, known are copolymers of a polymerizable monomer containing a polyfluoroalkyl group (hereinafter abbreviated as “Rf group”) and a hydrophilic group-containing polymerizable monomer (cf. JP-A-59-204980 and JP-A-62-7782).

In order to obtain these polymers, a large amount of an organic solvent is necessary for the polymerization for the purpose of compatibilizing the Rf group-containing polymerizable monomer with the hydrophilic group-containing polymerizable monomer to give a homogeneous polymer.

In addition, usually, the carbon number of the Rf group in the Rf group-containing polymerizable monomer is substantially at least 8 (JP-A-53-134786 and JP-A-2000-290640).

The reason therefor is that the crystallinity of the Rf group is too low so that the oil repellency is vanished in air and the oily soil unremovably penetrates into the treated article, although the crystallinity of the Rf group is decreased by reducing the number of the Rf group and polymer mobility is increased for the purpose of obtaining sufficient a flip-flop property and exhibiting the soil releasability. The flip-flop property is the property that a surface molecular structure is changed depending on environments in air and in water, which is proposed by Sherman et al. [P. Sherman, S. Smith, B. Johannessen, Textile Research Journal, 39, 499(1969)].

When, however, the number of the Rf group is at least 8, there is a trend that a large amount of the organic solvent is necessary in the course of obtaining the homogeneous copolymer and the handling of the treated article is decreased.

Further, recently, with respect to a compound containing the Rf group having 8 carbon atoms obtained by telomerization, Federal Register (FR Vol. 68, No. 73/Apr. 16, 2003 [FRL-2303-8]) (http://www.epa.gov/opptintr/pfoa/pfoafr.pdf); EPA Environmental News FOR RELEASE: MONDAY APR. 14, 2003 EPA INTENSIFIES SCIENTIFIC INVESTIGATION OF A CHEMICAL PROCESSING AID (http://www.epa.gov/opptintr/pfoa/pfoaprs.pdf); and EPA OPPT FACT SHEET Apr. 14, 2003 (http://www.epa.gov/opptintr/pfoa/pfoafacts.pdf) have announced that a “telomer” may possibly metabolize or decompose to perfluorooctanoic acid (hereinafter referred to as “PFOA”).

EPA (Environmental Protection Agency of USA) has announced that the EPA intensifies the scientific investigation on PFOA (cf. EPA Report “PRELIMINARY RISK ASSESSMENT OF THE DEVELOPMENTAL TOXICITY ASSOCIATED WITH EXPOSURE TO PERFLUOROOCTANOIC ACID AND ITS SALTS” (http://www.epa.gov/opptintr/pfoa/pfoara.pdf)).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

An object of the present invention is to provide a soil release agent which comprises a copolymer containing a polyfluoroalkyl group having less than 8 carbon atoms, which comprises an organic solvent in a necessary minimum amount, and which has excellent soil releasability and good handling.

Means for Solving the Problems

The present invention provides a copolymer comprising:

(a) a fluorine-containing acrylate having a linear or branched polyfluoroalkyl group having less than 8 carbon atoms wherein a hydrogen atom at alpha-position may be substituted, and (b) a fluorine-free (meth)acrylate having an oxyalkylene group.

The copolymer of the present invention acts as an active component of a soil release agent.

EFFECTS OF THE INVENTION

Since the soil release agent of the present invention has the increased compatibility with the fluorine-free monomer because of use of the Rf group having the shorter chain, the use amount of the organic solvent used as a polymerization solvent can be limited to the necessary minimum amount. Specifically, while the conventional solution polymerization needs the organic solvent in the amount of at least 2 to 10 times as large as the total of the polymerizable monomer, the polymerization according to the present invention needs the organic solvent in the amount of only at most 1.5 times.

In addition, water together with the organic solvent can be used as the polymerization solvent.

The present invention exhibits the soil releasability at least equal to that of the conventional soil release agent and has good handling or feeling.

In the prior arts, when the number of the carbon atoms in the Rf group is less than 8, the soil releasability is decreased. According to the present invention, however, the use of the polymerizable monomer having the Rf group having less than 8 carbon atoms has both high flip-flop property and the retention of oil repellency in air to give excellent soil releasability.

More excellent soil releasability can be obtained by combining two segments, that is, “ethylene oxide” and “propylene oxide” as alkylene oxide segments of the fluorine-free polymerizable monomer.

BEST MODE OF CARRYING OUT THE INVENTION

The component (a) is preferably of the- general formula (1):

H₂C═CXCOO—Y-Rf

wherein X is a hydrogen atom, a methyl group, a fluorine atom, a chlorine atom, a bromine atom, a iodine atom, a CFX¹X² group (wherein X¹ and X² is a hydrogen atom, a fluorine atom or a chlorine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group;

Y is an aliphatic group having 1 to 10 carbon atoms, an aromatic or cycloaliphatic group having 6 to 10 carbon atoms, a —CH₂CH₂N(R¹)SO₂— group (in which R¹ is an alkyl group having 1 to 4 carbon atoms) or a —CH₂CH(OY¹)CH₂— group (in which Y¹ is a hydrogen atom or an acetyl group); and

Rf is a linear or branched polyfluoroalkyl group having less than 8 carbon atoms.

X may be a fluorine atom, a chlorine atom, a bromine atom, a iodine atom, a CFX¹X² group (wherein X¹ and X² is a hydrogen atom, a fluorine atom or a chlorine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group.

In the component (a), the Rf group is preferably a perfluoroalkyl group. The carbon number of the Rf group may be from 1 to 6, particularly from 1 to 4, for example, 4. Examples of the Rf group are —CF₃, —CF₂CF₃, —CF₂CF₂CF₃, —CF (CF₃)₂, —CF₂CF₂CF₂CF₃, —CF₂CF(CF₃)₂, —C(CF₃)₃, —(CF₂)₄CF₃, —(CF₂)₂CF(CF₃)₂, —CF₂C(CF₃)₃, —CF(CF₃)CF₂CF₂CF₃, —(CF₂)₅CF₃ and —(CF₂)₃CF(CF₃)₂.

Examples of the component (a) are the followings, to which the present invention is not limited.

wherein Rf is a linear or branched fluoroalkyl group having 1 to 6 carbon atoms.

The component (a) may be a mixture of at least two.

In the component (b), the oxyalkylene group is preferably an oxyethylene group, an oxypropylene group or a combination of these two.

The component (b) is preferably a compound having at least one (particularly, one) carbon-carbon double bond. The component (b) may be a (meth)acrylate (that is, an acrylate or methacrylate) having oxyalkylene group. The number of oxyalkylene groups may be from 1 to 30.

The component (b) is preferably of the general formula (2):

H₂C═CXCOO—(RO)_(n)—X

wherein X is a hydrogen atom or a methyl group, R is an alkylene group having 2 to 6 carbon atoms, and n is an integer of 1 to 50.

n may be particularly from 1 to 30, for example, from 2 to 20.

The component (b) is preferably the following combination of two components.

Component (b-1): a compound wherein R in the general formula (2) is ethylene

Component (b-2): a compound wherein R in the general formula (2) is propylene

The weight ratio of the component (b-1) to the component (b-2) may be from 95:5 to 5:95, for example, from 80:20 to 20:80.

Specific examples of the component (b) are, for example, the followings, to which the components (b) is not limited.

H₂C═CHCOO—CH₂CH₂O—H

H₂C═C(CH₃)COO—CH₂CH₂O—H

H₂C═CHCOO—(CH₂CH₂O)₉—H

H₂C═C(CH₃)COO—(CH₂CH₂O)₉—H

H₂C═C(CH₃)COO—(CH₂CH₂O)₉—CH₃

H₂C═C(CH₃)COO—(CH₂CH₂O)₅—CH₃

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)₉—H

H₂C═CHCOO—(CH₂CH(CH₃)O)₉—H

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)₉—CH₃

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)₁₂—CH₃

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)₄₀—CH₃

H₂C═C(CH₃)COO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃

The component (b) may be a mixture of at least two.

In the copolymer of the present invention, the amount of the component (a) may be from 20 to 90% by weight, preferably from 30 to 80% by weight, for example, from 35 to 75% by weight, based on the copolymer. The amount of 20% by weight to 90% by weight can give high soil releasability and can prevent the penetration of oily soil.

The amount of the component (b) may be from 10 to 80% by weight, preferably from 20 to 70% by weight, for example, from 25 to 65% by weight, based on the copolymer. The amount of 10 to 80% by weight can give high soil releasability and can prevent the penetration of oily soil.

The copolymer of the present invention may contain another polymerizable monomer [component (c)], particularly a fluorine-free monomer for the purpose of improving the durability of soil releasability.

Examples of the component (c) include, for example, diacetoneacrylamide, (meth)acrylamide, N-methylol-acrylamide, hydroxymethyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, butadiene, chloroprene, glycidyl (meth)acrylate, maleic acid derivative, vinyl chloride, glycerol (meth)acrylate, styrene, acetoacetoxyethyl (meth)acrylate and alkyl (meth)acrylate, to which the component (c) is not limited.

The amount of the component (c) may be preferably from 0 to 40% by weight, more preferably from 0 to 30% by weight, for example, from 0.1 to 20% by weight, based on the copolymer. The component (c) may be a mixture of at least two.

The number-average molecular weight of the copolymer of the present invention may be from 1,000 to 1,000,000, preferably from 5,000 to 900,000. The molecular weight of 1,000 to 1,000,000 can give high soil releasability and high viscosity of polymerization liquid giving the easy handling. The molecular weight is measured by a gel permeation chromatography in terms of polystyrene.

The copolymer of the present invention may be a random copolymer, a block copolymer or a graft copolymer.

A polymerization method of producing the copolymer of the present invention is not limited. Various polymerization methods such as a bulk polymerization, a solution polymerization, an emulsion polymerization and a radiation polymerization can be selected. For example, a solution polymerization using an organic solvent and an emulsion polymerization using both an organic solvent and water are generally selected. A treatment liquid is produced by diluting a reaction mixture with water after the polymerization.

Examples of the organic solvent include ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and methyl acetate; glycols such as propylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol and tripropylene glycol; and alcohols such as ethyl alcohol and isopropanol.

The amount of the organic solvent is from 0 to 2 parts by weight, preferably from 0 to 1.5 parts by weight, based on 1 part of the copolymer. The polymerization is possible under the amount of at least 2 parts. A lower limit of the amount of organic solvent may be 0.1 parts by weight.

As the emulsifying agent for the emulsion polymerization, various emulsifying agents such as an anionic emulsifying agent, a cationic emulsifying agent and a nonionic emulsifying agent can be used.

A polymerization initiator such as a peroxide compound, an azo compound and a persulfate compound can be used. For the polymerization, the conventionally known mercapto group-containing compounds may be used for the purpose of molecular weight control. Examples thereof include 2-mercaptoethanol and alkyl mercaptan.

The thus produced copolymer is optionally diluted with water and can be applied as a soil release agent to a substrate by an arbitrary method. Examples of application method include an immersion coating and a spray coating. In the present invention, the “treatment” means that a fluorine-containing copolymer, which is an active compound of the soil release agent, is adhered to the treated article (that is, the substrate). The treatment gives the result that the treated article exhibits the soil releasability and water- and oil-repellency.

If necessary, another blender may used. Examples of the blender include water- and oil-repellent agents, crease-proofing agents, shrink-proof agents, antimicrobial agents, pigments and paints.

The substrate, to which the soil release agent of the present invention has been applied, may be subjected to the curing, if necessary.

The soil release agent of the present invention comprises the copolymer and a liquid medium (an organic solvent and/or water). In the soil release agent, the concentration of the copolymer may be from 0.1% to 90.0% by weight, for example, from 1% to 70% by weight. The soil release agent may be in the form of a solution, an emulsion or the like.

The treated article include a textile, masonry, a filter (for example, an electrostatic filter), a dust protective mask, glass, paper, wood, leather, fur, asbestos, brick, cement, metal and oxide, ceramics, plastics, a coated surface and a plaster, to which the treated article is not limited.

EXAMPLES

The following Examples, Comparative Examples and Test Examples are specifically illustrated but are not to be construed to limit the scope of the invention.

In the followings, parts and % are parts by weight or % by weight, unless otherwise specified.

The test for determining the soil releasability (SR property) is conducted by using a textile as follows. A test cloth in 7 cm×7 cm square is spread on a piece of blotting paper horizontally spread and then one drop of a soil which is a dispersion of carbon black (0.1% by weight) in triolein is dropped on the test cloth. A polyethylene sheet is positioned on the test cloth and a weight of 500 g in weight is positioned on the polyethylene sheet. After 60 seconds, the weight and the polyethylene sheet are removed. The test cloth is kept standing at a room temperature for 24 hours to adhere a soil to the test cloth. The test cloth and a ballast cloth together having a total weight of 500 g, and a cleaning agent (12.5 g) (trade name: SUPER COMPACT TOP manufactured by Lion Corporation) are charged into an electrical washer. The test cloth is washed at a bath amount of 25 L and a bath temperature of 40° C. for 5 minutes, then rinsed and dried at room temperature. The state of the remaining stain of the dried test cloth is compared with a standard photograph plate so that the soil releasability is expressed by the corresponding determined grade (cf. Table 1). The standard photograph plate is one according to AATCC-TM130-2000 (American Association of Textile Chemists and Colorists, Test Method 130-2000)

[Table 1]

TABLE 1 Determined grade of soil releasability Determined grade Criteria 1.0 Stain remarkably remains 2.0 Stain considerably remains 3.0 Stain slightly remains 4.0 Stain is not noticeable 5.0 Stain does not remain

The oil repellency test is conducted by using a textile according to AATCC-TM118-2000. The test cloth is spread horizontally and a test liquid shown in Table 2 is dropped on the test cloth. The penetration state is determined after 30 seconds. When the oil repellency is low, an oily soil is penetrated into the treated article so that the removal of the soil is difficult. Thus, the oil repellency is an important indication in the same position as the soil releasability (SR property).

[Table 2]

TABLE 2 Determined grade of oil repellency Oil Surface tension repellency Test liquid (dyne/cm, 25° C.) 8 n-Heptane 20.0 7 n-Octane 21.8 6 n-Decane 23.5 5 n-Dodecane 25.0 4 n-Tetradecane 26.7 3 n-Hexadecane 27.3 2 Mixture liquid of 29.6 n-Hexadecane 35/nujol 65 1 Nujol 31.2 0 Inferior to 1 —

The handling test is conducted by using a textile. The hand feeling of the test cloth is determined in the following determination standard.

Good: Same feeling as an untreated cloth:

Fair: Slightly harder feeling than an untreated cloth

Bad: Apparently harder feeling than an untreated cloth

Reference Test

Various combinations of polymerizable monomers are used to determine the compatibility of polymerizable monomers and the homogeneity of a polymerization liquid in a given solvent for the purpose of supporting that the use of a polymerizable monomer having a short chain Rf group improves the compatibility with a fluorine-free polymerizable monomer to minimize the use amount of an organic solvent which is a polymerization solvent.

The compatibility of the polymerizable monomers is evaluated as follows:

Good: homogeneous

Fair: Dispersed

Bad: Separated

The post-polymerization state (that is, the state after polymerization) is evaluated as follows:

Good: Homogeneous liquid state is maintained

Bad: Homogeneous liquid state is not maintained

The results confirmed that the use of specified polymerizable monomers having the Rf group having less than 8 carbon atoms improves the compatibility with the fluorine-free polymerizable monomer to realize the homogeneous polymerization under the low amount of the organic solvent which is the polymerization solvent.

Synthetic Example 1

A monomer (hereinafter referred to as “13FA”) (10 g) of the formula:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

and each of monomers (hereinafter referred to as “MPOEMA”) (10 g) of the formula:

H₂C═C(CH₃)COO—(CH₂CH₂O)_(n)—CH₃

wherein n is 4, 8 or 12 were mixed. The compatibility at 25° C. was observed. Further, isopropanol (20 g) was added to each of mixtures (20 g), charged into a four-necked flask and heated at 75° C. Oxygen in the system was sufficiently substituted with nitrogen, and then azobisisobutyronitrile (0.05 g) was added twice at an interval of one hour to conduct the polymerization. The state of the liquid was observed. In addition, the same polymerization was repeated with changing isopropanol to acetone and conducting the polymerization in an autoclave, and then the state of the liquid was observed. The results are shown in Table 3.

Synthetic Example 2

The same procedure as in Synthetic Example 1 was repeated except that the monomer 13FA used in Synthetic Example 1 was replaced by a monomer (hereinafter referred to as “αCL-13FA”) of the formula:

H₂C═CClCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

The results are shown in Table 3.

Synthetic Example 3

The same procedure as in Synthetic Example 1 was repeated except that the monomer MPOEMA used in Synthetic Example 1 was replaced by a monomer (hereinafter referred to as “POPMA”) of the formula:

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)_(n)—H

(n=5, 9 or 13).

The results are shown in Table 4.

Synthetic Example 4

The same procedure as in Synthetic Example 3 was repeated except that the monomer 13FA used in Synthetic Example 3 was replaced by the monomer αCL-13FA.

The results are shown in Table 4.

Comparative Synthetic Example 1

The same procedure as in Synthetic Example 1 was repeated except that the monomer 13FA was replaced by a monomer (hereinafter referred to as “17FA”) of the formula:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₃CF₂CF₃

The results are shown in Table 3.

Comparative Synthetic Example 2

The same procedure as in Synthetic Example 1 was repeated except that the monomer 13FA was replaced by the monomer 17FA and the monomer MPOEMA was replaced by the monomer POPMA.

The results are shown in Table 4.

[Table 3]

TABLE 3 Result 1 of Synthetic Examples Number of n in Post- Post- (CH₂CH₂O)_(n) in Compatibility polymerization polymerization Example No. MPOEMA with FA state in IPA state in acetone Synthetic Example 1 4 Good Good Good (Monomer13FA) 8 Good Good Good 12 Good Good Good Synthetic Example 2 4 Good Good Good (αCL-13FA) 8 Good Good Good 12 Good Good Good Comparative Synthetic 4 Bad Bad, Gelation Bad, Gelation Example 1 8 Bad Bad, Gelation Bad, Gelation (17FA) 12 Bad Bad, Gelation Bad, Gelation Compatibility with FA:

Good: homogeneous

Fair: Dispersed

Bad: Separated

Post-polymerization state:

Good: Homogeneous liquid state is maintained

Bad: Homogeneous liquid state is not maintained

13FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

αCL-13FA:

H₂C═CClCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

17FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₃CF₂CF₃

MPOEMA:

H₂C═C(CH₃)COO—(CH₂CH₂O)_(n)—CH₃

FA: General term of 13FA, αCL-13FA and 17FA

IPA: Isopropanol [Table 4]

TABLE 4 Result 2 of Synthetic Examples Number of n in Post- Post- (CH₂CH(CH₃)O)_(n) Compatibility polymerization polymerization Example No. in POPMA with FA state in IPA state in acetone Synthetic Example 3 5 Good Good Good (13FA) 9 Good Good Good 13 Good Good Good Synthetic Example 4 5 Good Good Good (αCL-13FA) 9 Good Good Good 13 Good Good Good Comparative Synthetic 5 Bad Bad, Gelation Bad, Gelation Example 2 9 Bad Bad, Gelation Bad, Gelation (17FA) 13 Bad Bad, Gelation Bad, Gelation Compatibility with FA:

Good: homogeneous

Fair: Dispersed

Bad: Separated

Post-polymerization state:

Good: Homogeneous liquid state is maintained

Bad: Homogeneous liquid state is not maintained

13FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

αCL-13FA:

H₂C═CClCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

17FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₃CF₂CF₃

POPMA:

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)_(n)—H

FA: General term of 13FA, αCL-13FA and 17FA

IPA: Isopropanol Example 1

A monomer (hereinafter referred to as “13FA”) (10 g) of the formula:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

a monomer (hereinafter referred to as “PE200”) (10 g) of the formula:

H₂C═C(CH₃)COO—(CH₂CH₂O)_(4.5)—H

wherein the average number of oxyethylene group is 4.5, and isopropyl alcohol (20 g) were charged into a four-necked flask. Oxygen in the system was sufficiently substituted with nitrogen, and then azobisisobutyronitrile (0.05 g) was added twice at an interval of one hour to conduct the polymerization. A gel permeation chromatography of the resultant polymerization liquid as such for measuring the molecular weight confirmed that peaks derived from the monomers disappeared and that peaks derived from the copolymer were formed.

Example 2

The same polymerization and analysis as in Example 1 were repeated except that the monomer 13FA used in Example 1 was replaced by a monomer (hereinafter referred to as “αCL-13FA”) of the formula:

H₂C═CClCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

Example 3

The same polymerization and analysis as in Example 1 were repeated except that the monomer 13FA used in Example 1 was replaced by a monomer (hereinafter referred to as “13FMA”) of the formula:

H₂C═C(CH₃)COO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

Example 4

The same polymerization and analysis as in Example 1 were repeated except that the monomer 13FA used in Example 1 was replaced by a monomer (hereinafter referred to as “αF-13FA”) of the formula:

H₂C═CFCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

Example 5

The same polymerization and analysis as in Example 1 were repeated except that the monomer 13FA used in Example 1 was replaced by a monomer (hereinafter referred to as “13FCHMA”) of the formula:

Example 6

The same polymerization and analysis as in Example 1 were repeated except that 6 g among 10 g of PE200 used in Example 1 was replaced by a monomer (hereinafter referred to as “PP800”) of the formula:

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)₁₂—H

Example 7

The same polymerization and analysis as in Example 1 were repeated except that 10 g of PE200 used in Example 1 was replaced by 4 g of PP800 and 6 g of a monomer (hereinafter referred to as “PME400”) of the formula:

H₂C═C(CH₃)COO—(CH₂CH₂O)₉—CH₃

Comparative Example 1

The same polymerization as in Example 1 was repeated except that 13FA was replaced with a monomer (hereinafter referred to as “17FA”) of the formula:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₃CF₂CF₃

Since a polymerization liquid was not recovered, the reaction was discontinued and the reaction mixture was discarded.

Comparative Example 2

The same polymerization and analysis as in Example 1 were repeated except that 13FA used in Example 1 was replaced by 17FA and the amount of isopropyl alcohol was increased to 40 g.

Comparative Example 3

The same polymerization and analysis as in Example 1 were repeated except that 10 g of 13FA used in Example 1 was replaced by 6 g of 17FA and 4 g of a monomer (hereinafter referred to as “21FA”) of the formula:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₄CF₂CF₃

and the amount of isopropyl alcohol was increased to 60 g.

Comparative Example 4

The same polymerization and analysis as in Example 1 were repeated except that 13FA (10 g) used in Example 1 was replaced by 17FA (6 g) and the amount of PE200 was increased to 14 g.

Test Example 1

The polymerization liquid obtained in Example 1 was diluted to the concentration of 1% solid with water to give a treatment bath. A cotton twill cloth and a 65% polyester/35% cotton mixture twill cloth were immersed in this treatment bath and squeezed by rolls to give a wet pickup of 60 mass % and 55 mass %, respectively. The clothes were dried at 110° C. for 2 minutes and heat-treated at 160° C. for 1 minute to complete the treatment with the soil release agent. The soil releasability and the oil repellency of these clothes were measured. The results are shown in Table 5.

Test Examples 2 to 7 and Comparative Test Examples 2 to 4

The procedure for test as in Test Example 1 was repeated except that the polymerization liquid was changed to each of those obtained in Examples 2 to 7 and Comparative Examples 2 to 4.

[Table 5]

TABLE 5 Results of Test Examples IPA amount Molecular Soil Oil Example based on weight releasability repellency Handling No. Type of polymer polymer (Mn) C PET/C C PET/C C PET/C Test 13FA/PE200 1.0 time 33000 3.0 5.0 4 6 Good Good Example 1 (50/50) Test αCL-13FA/PE200 1.0 time 29000 3.0 5.0 4 6 Good Good Example 2 (50/50) Test 13FMA/PE200 1.0 time 30000 3.0 5.0 4 6 Good Good Example 3 (50/50) Test αF-13FA/PE200 1.0 time 32000 3.0 5.0 4 6 Good Good Example 4 (50/50) Test 13FCHMA/PE200 1.0 time 3000 3.0 5.0 4 6 Good Good Example 5 (50/50) Test 13FA/PP800/PE200 1.0 time 28000 4.0 5.0 5 8 Good Good Example 6 (50/30/20) Test 13FA/PP800/PME400 1.0 time 28000 4.0 5.0 5 7 Good Good Example 7 (50/20/30) Com. Test 17FA/PE200 1.0 time Liquid state was not maintained after Example 1 (50/50) polymerization Com. Test 17FA/PE200 2.0 times 18000 3.0 5.0 4 6 Fair Fair Example 2 (50/50) Com. Test 17FA/21FA/PE200 3.0 times 22000 2.5 4.0 4 6 Bad Bad Example 3 (30/20/50) Com. Test 17FA/PE200 1.0 time 20000 1.0 2.0 2 3 Good Good Example 4 (30/70)

13FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

αCL-13FA:

H₂C═CClCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

13FMA:

H₂C═C(CH₃)COO—CH₂CH₂—(CF₂CF)₂CF₂CF₃

αF-13FA:

H₂C═CFCOO—CH₂CH₂—(CF₂CF₂)₂CF₂CF₃

13FCHMA:

17FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₃CF₂CF₃

21FA:

H₂C═CHCOO—CH₂CH₂—(CF₂CF₂)₄CF₂CF₃

PE200:

H₂C═C(CH₃)COO—(CH₂CH₂O)_(4.5)—H

PP800:

H₂C═C(CH₃)COO—(CH₂CH(CH₃)O)₁₂—H

PME400:

H₂C═C(CH₃)COO—(CH₂CH₂O)₉—CH₃

IPA: Isopropanol

C: Cotton twill cloth PET/C: 65% polyester/35% cotton mixture twill cloth 

1. A copolymer comprising: (a) a fluorine-containing acrylate having a linear or branched polyfluoroalkyl group having less than 8 carbon atoms wherein a hydrogen atom at alpha-position may be substituted, and (b) a fluorine-free (meth)acrylate having an oxyalkylene group.
 2. The copolymer according to claim 1, wherein the component (a) is of the general formula (1): H₂C═CXCOO—Y-Rf wherein X is a hydrogen atom, a methyl group, a fluorine atom, a chlorine atom, a bromine atom, a iodine atom, a CFX¹X² group (wherein X¹ and X² is a hydrogen atom, a fluorine atom or a chlorine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group; Y is an aliphatic group having 1 to 10 carbon atoms, an aromatic or cycloaliphatic group having 6 to 10 carbon atoms, a —CH₂CH₂N(R¹)SO₂— group (in which R¹ is an alkyl group having 1 to 4 carbon atoms) or a —CH₂CH(OY¹)CH₂— group (in which Y¹ is a hydrogen atom or an acetyl group); and Rf is a linear or branched polyfluoroalkyl group having less than 8 carbon atoms.
 3. The copolymer according to claim 2, wherein X is a fluorine atom, a chlorine atom, a bromine atom, a iodine atom, a CFX¹X² group (wherein X¹ and X² is a hydrogen atom, a fluorine atom or a chlorine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group.
 4. The copolymer according to claim 1, wherein the component (b) is of the general formula (2): H₂C═CXCOO—(RO)_(n)—X wherein X is a hydrogen atom or a methyl group, R is an alkylene group having 2 to 6 carbon atoms, and n is an integer of 1 to
 50. 5. The copolymer according to claim 1, wherein the amount of the component (a) may be from 20 to 90% by weight, and the amount of the component (b) is from 10 to 80% by weight, based on the copolymer.
 6. The copolymer according to claim 1, wherein the number-average molecular weight of the copolymer is from 1,000 to 1,000,000.
 7. The copolymer according to claim 1, wherein the component (b) comprises the following combination of two components: Component (b-1): a compound wherein R in the general formula (2) is ethylene, and Component (b-2): a compound wherein R in the general formula (2) is propylene.
 8. The copolymer according to claim 7, wherein the weight ratio of the component (b-1) to the component (b-2) is from 95:5 to 5:95.
 9. A soil release agent comprising the copolymer according to claim
 1. 10. The soil release agent according to claim 9, which further contains a liquid medium.
 11. A method of treating a substrate, which comprises treating the substrate with the soil release agent according to claim
 9. 12. A textile treated with the soil release agent according to claim
 9. 